Buttonhole sewing machine



1933- H. CORRALL ET AL BUTTONHOLE SEWING MACHINE Filed Jul 19, 1932 2 Sheets-Sheet l QM NW NM NM m V, FrLE L M w L ww Nov. 21, 1933. H. CORRALL ET AL BUTTONHOLE SEWING MACHINE Filed- July 19, 1932 2 Sheets-Sheet 2 awe/WWO Herbal-f ('arrall James-Hgytk A z? Patented Nov. 21, 1933 UNITED STATES FATE r OFFICE.

BUTTONHOLE SEWING MACHINE Application July 19, 1932, Serial No. 623,326, and in Great Britain July 5, 1932 13 Claims. (01. 112-68) which carries a buttonhole cutting knife and is given an endwise reciprocatory impulse by the action of the stop-motion mechanism of the machine at the close of a buttonhole sewing period to cut the buttonhole slit.

The knife-bar is commonly mounted alongside the needlebar in the head of the machine at the free end of the overhanging gooseneck, and a rigid knife-bar stop is usually mounted on topof such head to arrest the knife-bar at the end of its upward or recovery motion following its downward or buttonhole-slit-cutting impulse. The knife-bar-stop is commonly made in the form of an inverted L the vertical stem of which is fixedly screwed into a threaded aperture in the top of the machine head, so that the horizontal portion of the stop overhangs the upper end of the knifebar. The repeated blows of the knife-bar against the kniie-bar-stop, caused by the knife-bar actuating mechanism, weaken the stop and result in breakage of the latter.

The present invention has for an object to provide an automatic buttonhole cutting and stitching means which is free from the heretofore experienced breakage oi parts of the buttonhole cutting mechanism.

With the above and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations, and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodimerit of the invention, from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

In the accompanying drawings, Fig. 1 is a side elevation of buttonhole sewing machine embodying the invention. Fig. 2 is a rear end elevation of the machine. Fig. 3 is a fragmentary horizontal sectional View on the line S-3, Fig. 1. Fig. 4c is a section on the line 44, Fig. 1, with the knife-bar in its lowest position, and Fig. 5 is a similar view with the knife-bar executing its recovery motion but below its upper limit of motion.

The machine is constructed with a frame having a bed 1 from which rises the standard 2 of the gooseneck including the overhanging arm 3 terminating in the head 4. The frame carries the usual stitch-forming mechanism including the reciprocating and laterally vibrating needle 5 which is driven in the usual manner from the main-shaft 6. The period of operation of the main-shaft 6 is controlled by the usual stopmotion device including the stop-cam 7 and upwardly spring-pressed stop-plunger 8 which is carried by the tilting stop-motion lever 9 fulcrumed on trunnion-screws 10. When the machine is in operation the stop-motion lever 9 and plunger 8 occupy an inclined position, as shown in dotted lines in Fig. 1, with the upper end of the plunger Bdisplaced inwardly from and out of range of the stop-cam7. At the end of the sewing operation the stop-motion lever 9 moves to its vertical position and carries the plunger 8 within range of the stop-cam 7'which has an eccentric plunger-depressing portion 11 leading to a stop-notch 12 into which the plunger 8 rises as the machine comes to rest.

The machine includes theusual lower worksupporting plate 13 and upperclarnp-foot 14 which are moved relative to the bed 1 by the usual connections with the feed-wheel 15 carried by the vertical feed-wheel shaft 16. The shaft 16 makes one revolution per buttonhole-producing cycle and is given a step-by-step rotarymotion by the usual connections actuated by the main-shaft 6.

The buttonhole-cutting mechanism includes the knife 1'7 connected to the lower end of the knife-bar 18 slidably mounted in the head 4 and connected by the link 19 to the lever 20 biased by the spring 20' and fulcrumed at 21 on the gooseneck arm 3. The lever 20 has fixed to its rearward end a stud-screw 22-which passes through a slot 23 in the upper end of a link 24 connected at its lower end at 25 to the forward end of the lever 26- fulcrumed at 2'? on the standard 2. The lever 26 is horizontally slotted at 28 to embrace the lateral stud 29 on the collar 8" fixed to the stop-motion plunger 8. A latcharm 30 fulcrumed at 31 upon the link 24 is formed with a shoulder 32 which at times engages under the stud-screw 22 on the lever 20 and couples ,the lever 20 to the lever 26 for the buttonholecutting operation. The latch-armBO has a lat-.

eral extension 33 which at times rests upon the end-extension 340i the arm 35 of a bell crank trip-lever, Fig. 3, the otherarm 36 of which carries a follower 3'7 in the path of a cam 38 on the fee -wheel-shaft 16. 7 I

When the machine is at rest, theparts are in the positions shown in full lines in Fig. 1 with the latch-arm 33 resting under the influence of the latch-biasing-spring '39 upon the trip-lever extension 34 and the cutter-lever 20 uncoupled from its actuating lever 26. The cam 38 is in the position shown in Fig. 3.

When the stop-motion lever 9 is tilted to its dotted line position, Fig. 1, to start the machine, the stop-motion plunger 8 is tilted out of the notch 12 of the stop-cam 7 and rises slightly under the influence of the stop-motion plunger spring 8 until the collar 8" on the plunger 8, Fig. 2, strikes the stop-shoulder 8 on the stopmotion lever 9. This up-motion of the plunger 8, which occurs when the machine is started, is suificient to swing the front end of the lever 26, Fig. 1, to its lower dotted line position and lower the latch-shoulder 32 so that it may, when later released, engage under the pin 22 on the lever 20.

As the sewing begins, the cam 38 is given a slow motion in the direction of the arrow, Fig. 3, and, when the sewing of the buttonhole is nearing completion, the cam 38 engages the follower 37 and swings the trip-lever 35, 36 sufliciently to remove the extension 34 from under the arm 33 of the latch whereupon the latch 30 is drawn over by the spring 39 so that its shoulder 32 engages under the pin-22 and couples the cutterlever 20 to the lever 26. The cam 38 passes the follower 3'7 and releases the trip-lever 35, 36 which is then swung by its spring 40 so that its extension 34 bears against the side of the latch-arm 33.

When the sewing operation is completed, the depression of the stop-motion plunger 8 by the eccentric portion 11 of. the stop-cam causes the levers 26 and 20 to move to their dotted line positions, Fig. 1, as the buttonhole-cutting-impulse is imparted to the knife-bar 18. This impulse raises the latch-arm 33 above the trip-arm-extension 34 which promptly moves under the same. On the recovery motion of the parts, the arm 33 strikes downwardly upon the trip-arm-extension 34 and ellects the uncoupling of the lever 20 from the lever 26 as the knife-bar 18 is moving upwardly and before the knife-bar reaches the upper limit of its movement.

Screwed into the threaded aperture 41 in the top of the head 4 is the shank 42 of the inverted L-shaped stop 43 the free end of which overhangs the upper end of the knife-bar l8 and has heretofore been provided with an inset buifer plug 44 of leather or copper. The lock-nut 45 holds the stop 43 rigidly in adjusted position.

Fitted to the upper end of the'knife-bar 18 is the pneumatic cap 46 having air-inlet holes 47 near its lower end. The cap 46 is free to align itself perfectly with the knife-bar 18 and is closely but freely fitted to the-k'nife-bar so as to retard the upstroke of the knife-bar by a pneumatic cushioning action after the knife-bar is disconnected from the stop-motion plunger 8.

It will be understood that the stop-motion plunger spring 8 is relatively strong, whereas the recovery spring 20' for the lever 20 is relatively weak. The up-motion of the stop-motion plunger 8 into the stop-notch 12 imparts a strong upward impulse to the knife-bar 18 as is desirable in the early part of the up-stroke of the knife-bar to insure withdrawal of the knife 17 fromthe work. During the early portion of the up-stroke of the knife-bar 18 the retarding action of the pneumatic cap 46 is very slight and as a quickly and softly arrests the speed of up-motion of the knife-bar 18 and permits it to slowly finish its up-stroke under the influence of the weaker spring 20 only.

It will be understood that the stop-motion device including the stop-cam 7, plunger 8 with its strong recovery spring 8, and lever 26, constitute automatically operated mechanism for actuating the buttonhole cutter 17. The latching mechanism between the levers 26 and 20 constitutes means for disconnecting such automatically operated mechanism from the cutter 17 during the retracting movement or the latter. The pneumatic cap 46 effectively retards completion of the retracting movement of the cutter 1'7 after disconnection of the latter from the stop-motion plun er 8, and the spring 20 holds the cutter in retracted position.

Having thus set forth the nature of the invent-ion, what we claim herein is:-

1. In a buttonhole sewing machine, a buttonhole cutter, automatically operated mechanism for actuating said cutter in a direction to cut the buttonhole and for initiating the return of the cutter to initial position, means for discon-' necting said automatically operated mechanism from said cutter after the return motion of the cutter has been initiated but before such motion has been completed, a device for retarding completion of the return motion of the cutter, and means for completing the return motion of the cutter to initial position against the resistance of said retarding device.

2. In a buttonhole sewing machine, a buttonhole cutter, automatically operated mechanism for actuating said cutter in a direction to cut the buttonhole and for initiating the retracting movement of thecutter to forcibly remove the latter from the work, means for disconnecting said automatically operated mechanism from said cutter after the retracting movement of the cutter has been initiated, a pneumatic device acting to retard completion of the retracting movement of the cutter, and means effective to complete the retracting movement of the cutter 'in opposition to said pneumatic retarding device after disconnection from the-cutter of said automatically operated mechanism.

' 3. In a buttonhole sewing machine, the combination with the frame, stitch-forming mechanism, work-clamp and main-shaft connected to drive the stitch-forming mechanism and to relatively move the stitch-forming mechanism and work-clamp to sew about a buttonhole, of buttonhole cutting mechanism including an endwise reciprocatory knife-bar journaled in said frame, a knife connected to be actuated by said knifebar, automatic actuating means applied to said knife-bar for projecting said knife through the work and forceably withdrawing it therefrom, means for disconnecting said knife-bar from said automatic actuating means after the return stroke of the knife-bar has been initiated but before it has been completed, a spring for cornpleting the return stroke of said knife-bar afterilii the latter has been disconnected from said automatic actuating means, and pneumatic means for retarding completion of the return stroke of the knife-bar by said relatively weak spring after ani'sm, work-clamp and main-shaft connected to, drive the stitch-forming mechanism and to relatively move the stitch-forming mechanism and work-clamp to sew about a buttonhole, of buttonhole cutting mechanism including an endwise reciprocatory knife-bar journaled in said frame, a knife connected to be actuated by said knife-bar, automatic actuating means applied to said knife-bar for projecting said knife through the work and forceably withdrawing it therefrom, pneiunatic retarding means for applying a resistance to the motion of said knife-bar on the return stroke of the latter, means for disconnecting said knife-bar from said actuating means while said knife-bar is under the influence of said pneumatic retarding means and before its return stroke is completed, and means for completing the return stroke of said knife-bar to initial position and for holding such knife-bar in initial position.

5. In a buttonhole sewing machine, the combination with the machine frame, of an endwise reciprccatory knife-bar journaled in said frame, buttonhole cutting knife connected to be operated by said knife-bar, a relatively weak spring constantly biasing said knife-bar upwardly, means for driving said knife-bar downwardly, a relatively strong spring acting in addition to said weak spring to initiate the recovery motion of the knife-bar following its down-stroke, means for disconnecting said knife-bar from said strong spring before the up-stroke of the knife-bar is completed, and pneumatic buffer means for retarding the latter portion of the up-stroke of the knife-bar under the recovery influence of the weak spring only.

G, In a buttonhole sewing machine, the combination with stitch-forming mechanism, a workclamp, means for relatively moving the stitchiorming mechanism and work-clamp to sew about a buttonhole, a main-shaft, a stop-motion device, buttonhole cutting mechanism including a vertically reciprocatory knife-bar actuated by the stop-motion device, means connected to the stop-motion device for imparting a cutting impulse to said knife-bar at the close of a sewing operation, means for initiating the recovery motion of the knife-bar, means for discoimecting the knife-bar from said last mentioned means before said recovery motion is completed, pneumatic means for retarding the latter portion of the recovery motion of the knife-bar, and means for completing the recovery motion of the knifebar against the resistance of said pneumatic means.

7. In a buttonhole sewing machine, the combination with stitch-forming mechanism, a work-c mp, means for relatively moving the stitch-forming mechanism and work-clamp to sew about a buttonhole, a main-shaft, a stopmotion device, buttonhole cutting mechanism including vertically reciprocatory knife-bar actuated by the stop-motion device, a knife-bar stop disposed above the upper end of the knife-bar, and a pneui atic buffer device fitted to the upper end of the knife-bar below said stop, said device being free of connection with said stop but adapted to engage the latter on the up-stroke of the knife-bar.

8. In a buttonhole sewing machine, a gooseneck terminating at its free end in a head, a knife-bar slidably mounted in said head, the upper end of said knife-bar projec "ng above the upper end of said head, a knife-bar stop rigidly mounted on top of said head, and a pneumatic buffer cap slidably fitted to the upper end of said knife-bar below said stop, said cap being free of connection with said head and stop but adapted to alternately engage said head and stop on the down and up strokes, respectively, of the knifebar, said cap having an air admission passageway in its side-wall above the lower limit of motion of the upper end of the knife-bar.

9. In a buttonhole sewing machine, a gooseneck terminating at its free end in a head, a knife-bar slidably mounted in said head, the upper end of said knife-bar projecting above the upper end of said head, a knife-bar stop rigidly mounted on top of said head and vertically adjustable relative thereto, and a pneumatic buffer cap slidably fitted to the upper end of said knifebar below said stop, said cap being free of connection with said head and stop but adapted to alternately engage said head and stop on the down and up strokes, respectively, of the knifebar.

10. In a sewing machine, a frame, an endwise reciprocatory knife-bar journaled in said frame, one end of said knife-bar projecting beyond said frame, a knife-bar stop rigid with said frame and located in position to be en aged by the projecting end of said knife-bar, and a pneumatic buffer cap free on said projecting end of said knifebar, said buffer cap being free of connection with said frame and knife-bar stop and alternately abutting the frame and stop, respectively.

11. In a sewing machine, a frame having spaced stops, a knife-bar mounted in said frame for endwise reciprocatory motion and having a free end terminating between said stops, and a buffer cap free on said end of the knife-bar and alternately abutting said stops.

12. A buttonhole sewing machine having, in combination, a frame including a bed and gooseneck terminating in a head, stitch-forming mechanism, a work-clamp, a main-shaft, a stopmotion device for said main-shaft, a buttonhole cutting knife, an upwardly spring-biased vertically reciprocatory knife-bar mounted in said head and connected to be operated by said stopmotion device, a cap pneumatically fitted to and enclosing the upper end of said knife-bar, and means permitting said knife-bar to execute the latter portion of its recovery motion under the influence of its spring with a retarded motion independently of the stop motion device.

13. In a buttonhole sewing machine, stitchforming mechanism, a work-clamp, a mainshaft, a stop-motion device for the main-shaft including a tilting stop-motion lever, a springpressed plunger carried by said lever, and a stopcam on the main-shaft having an eccentric plunger-depressing portion followed by a stopnotch into which the plunger rises under the influence of its spring, a buttonhole cutting knife, an upwardly springbiased vertically reciprocatory knife-bar, an operative connection between said stop-motion plunger and knife-bar for imparting a down-motion to the knife-bar from the down-motion of the stop-motion plunger, means for disconnecting the knife-bar from said plunger after the buttonhole has been cut, pneumatic means for retarding the latter portion of the recovery motion of the knife-bar after the stop-motion plunger is finally seated in the stop-notch of said stop-cam, and means for j 

